Sequencing switch



Jan. 7, 1969 R. E. SWALLOW ET AL 3,420,175

SEQUENCING SWITCH Filed April 5, 1967 IIlIIIIIIIIlIllIII/l A F l G. 3.

INVENTORS. ROBERT E. SWALLOW JERRY R. MILLER 5 BY v. c. MULLER ROY MILLER ATTORNEYS.

United States Patent 7 Claims ABSTRACT OF THE DISCLOSURE Electric circuit for use with aircraft carried dispenser which sequentially permits dispenser door to open and then allows ram air to enter same for discharging its contents.

In the prior art it has been the practice to dispense materials, such as chemicals, bomblets, leaflets or rations from an aircraft carried container or pod by opening a rear door on the pod and then permitting ram air to enter the front end of the pod for ejecting the materials. Such a device is disclosed in the patent application of Jack A. Myers, Ser. No. 415,828, filed Der. 3, 1964, now US. Patent No. 3,308,719. In the application, just referred to, parallel electric circuits are disclosed which simultaneously effect opening of the rear door and a ram air closure. In a present embodiment, however, a rear door operated switch is provided which effects opening of the ram air closure when the door moves to open position, this sequence being necessary due to insufficient available current for operating both devices simultaneously. The embodiment just referred to has malfunctioned on occasion, allowing the door to open but not actuating the switch, thus either effecting retention of the materials in the pod or dispensing them over undesired areas. If the material was a corrosive chemical, contamination of the aircraft was also possible due to such malfunction.

One of the objects of the invention is to provide an improved sequentially operated circuit for use in the environment just described which effects opening of a ram air closure independent of the intended satisfactory previous functioning of a rear door.

Another object is to provide a fail-safe circuit which opens the ram air closure regardless of malfunctioning of the rear door and permits ram air to aid in opening it in event of malfunction.

A further object is to provide an intervalometer for establishing sequential circuits to a plurality of electrically initiated detonators or the like.

Still further objects, advantages and salient features will become more apparent from the description to follow, the appended claims and the accompanying drawing in which:

FIG. 1 is an elevation of the general environment of the invention;

FIG. 2 is an enlarged partial elevation of FIG. 1, portions being broken away;

FIG. 3 is a circuit employed in combination with specific elements illustrated in FIG. 2; and

FIG. 4 is a circuit, for use with a greater number of like elements.

Referring now to the drawing, FIG. 1, as in the patent application referred to, illustrates the environment of the invention in which a pod carried by an aircraft A, is employed to dispense materials when a door 21 is opened. FIG. 2 illustrates the pod which comprises a ram air orifice 16 at its forward end, closed by a frangible disk 17, which may be removed by initiating a detonator 18, and a hinged door 21 at its rear end which may be opened upon initiation of an explosive bolt, as described in the application referred to. For simplicity of disclosure, the door is illustrated with a detent 22 for retaining it closed, an explosive actuator 23 for moving the detent out of the path of the door, and a spring 24 for opening the door. As will be understood, expolsive actuator 23 includes a squib S and detonator 18 includes a squib 8;, the bridge wires of which when energized by electric current, initiate powder charges.

Referring now to FIG. 3, squibs S S form portions of a circuit which includes a silicon controlled rectifier SCR and a pair of resistors R R as shown, the values of which are:

In operation, an aircraft firing signal E is applied at the desired time. At this time SCR has high resistance, its gate voltage being less than E and no appreciable current flows through SCR and S The current first flows through R and S which fires S and opens the circuit across S The SCR gate voltage now approaches the supply voltage causing it to turn on, firing S The sequence occurs in 7 milliseconds or less. The value of R is not critical and may be chosen to protect SCR As will now be apparent, the removal of the ram air closure 17 is not dependent upon the satisfactory opening of door 21 and the closing of a switch by the opening of the door, as in the prior art referred to, and in the event of some malfunction in the opening of the door, the ram air will aid in opening it.

In the invention so far described, only two squibs are disclosed which are fired at short intervals apart. FIG. 4 illustrates a like circuit for firing more than two squibs. In this circuit, S and S fire in sequence as previously described, followed by S to S in sequence, N being equal to the number of squibs.

Obviously many modifications and variations of the present invention are possible in the light of the above teachings. It is therefore to be understood that within the scope of the appended claims the invention may be practiced otherwise than as specifically described.

What is claimed is:

1. An apparatus of the type having a plurality of devices adapted to be operated in sequence, each having an explosive device associated therewith and each including an electric squib adapted to be fired for initiating same, the improvements, in combination, comprising:

(a) a resistor series connected to .a first squib across a source of supply voltage and a circuit ground, in the order named, and having a junction therebetween,

(b) an electronic switch series connected to another squib between the high potential side of the source of supply voltage and the reference ground and including a blocking gate electrode adapted to close the gate in response to a blocking signal, and

(c) means connecting said junction to said blocking gate for applying said blocking signal.

2. Apparatus in accordance with claim 1 including at least one more electronic switch and squib connected in like manner between the supply voltage and reference ground.

3. Apparatus in accordance with claim 1 wherein said means connecting said junction to said blocking gate includes a resistor.

4. Apparatus in accordance with claim 1 wherein the electronic switch is a silicon controlled rectifier.

5. Apparatus in accordance with claim 1 wherein one of said devices is an openable rear door on an aircraft 3 4 carried pod containing materials to be dispensed, and References Cited another of said deyices is a ram-air closure at the front UNITED STATES PATENTS end of the pod, said closure adapted to be opened lndependent of the opening of the door. 3099962 8/1963 Smlth 102-702 6. Apparatus in accordance with claim 5 wherein the 5 3,312,869 4/1967 Werner 1O2 702 electronic switch is a silicon controlled rectifier. 3,340,811 9/1967 Gauld 102 70'2 7. Apparatus in accordance with claim 6, said means p for connecting said junction to said blocking gate includes BENJAMIN BORCHELT Primary Examiner a resistor. VERLIN R. PENDERGRASS, Assistant Examiner. 

